Conventional techniques to illuminate street signs, light panels or other objects with Light-Emitting Diodes (LEDs) include placing the LED light sources at the back of the panel or object (i.e. “back-lit” type) with the light shining normally to the viewing surface (see for example U.S. Pat. Nos. 6,558,021 and 6,761,471). Back-lit light sources can be placed over a large area to illuminate a light panel or object with various shapes and sizes. As each individual light source can be placed wherever the installer wants, or can be adjusted after the initial placement, during construction, back lit light sources are flexible, user-friendly and easy-to-repair. However, depending on the emission pattern (e.g. divergence) and intensity of the light sources, a certain distance between the light sources and the viewing surface is required to enable an overall uniform and bright illumination of the entire viewing surface, because many LEDs emit most of their light in a relatively small cone of viewing angles (typically centered around the emission axis of the LED). Therefore, the light panel or object body cannot be built as thin as one may desire. For thin panel applications, there simply is insufficient mixing or homogenizing at the face panel because the light coming directly from the back of the panel is either transmitted through or reflected back at the face panel.
It is also known to place the LED light sources at the side of the panel or object (i.e. “edge-lit” type) with light beaming into a light transmitting/guiding medium that re-directs the light to the viewing surface (see for example U.S. Pat. No. 6,481,130). Edge-lit light sources can be placed along the surrounding periphery of the light panel or object which includes a light-guiding medium between the light source and the viewing surface. The distance between each individual light source can be adjusted to give various light intensities and uniformity, depending on the emitting pattern and intensity of the light sources. With edge-lit sources, a thinner light panel or object body can be built. However, patches of dark regions can result when the to be illuminated areas are located over long distances from the light sources. These dark regions can occur in oversized light panels or objects because the center portions of the panel are too far from the panel/object edges, and light intensity decreases significantly as the light travels over extended distances. In addition, panels/objects with complex shapes can be difficult to illuminate evenly from irregularly shaped panel/object edges.